RV-10 IO-540 Ignition System Decision

I was looking into my list of things I need to accomplish (still quite long) but I do need to start putting some thought into my electrical system. I have a while before this occurs but as they say “an ounce of forethought is worth a pound of”….or no wait maybe it was “an ounce of forethought is worth a pound of second thoughts, after thoughts and now doubt”? I can’t remember, but I do know researching one thing leads to fifteen other things. This is how I wound up needing to decide on my ignition system.

 

Caveat Lector

First let me point out that everything that I state below is all based on my research, readings, and questions as of March 2013. This information could be inadequate, outdated, or just wrong, especially as time moves on. The information came from making phone calls to vendors, reading installation manuals, and the following websites:

http://www.avweb.com/news/maint/182843-1.html
http://www.g3ignition.com/
http://www.emagair.com/
http://www.lightspeedengineering.com/Products/Ignition.htm
http://www.electroair.net/
http://www.flyefii.com/

  

Vans Aircraft Engine

A reference of what is “normal” from Van’s Aircraft.
The IO-540-D4A5 260hp engines are shipped with:

• SkyTech lightweight starters (might want to upgrade for reasons explained later)
• 149 tooth ring gears
• Dual magnetos (might want to replace with electronic ignition, the purpose of this post)
• Carburetors or Bendix fuel injection systems (Fuel injection is a must for me and I may want to replace with GAMI injectors as they provide a much more balanced fuel injection, but this is off topic for this post)
• Engine driven fuel pumps.

Parts included in the Firewall Forward Kit (this is not everything, there are a lot of little parts not listed here)

• Prop governor  
• Alternator  
• Exhaust system  (Upgrade to Vetterman Exhaust?)

IGNITION SYSTEMS

Now on to the ignition system discussion and we should begin with the classic magneto. The magneto is ancient technology by today’s standards. It is a simple system over 100 years old. Your lawnmower probably uses this system to generate its spark. For aircraft, two magnetos attach to the engine and are mechanically driven by the engine. In simplistic terms the drive turns a magnet and wound wire to produce electricity, like an alternator. (Visit this site for a descriptive explanation of its operations http://www.avweb.com/news/maint/182843-1.html). The energy is then dispersed by a small distributor on top of the magneto and into the spark plugs. Both magnetos are set to fire at the same time. There are two spark plugs in each cylinder and two magnetos so if one system goes down the engine still runs on the other. If the entire electrical system shuts down the magnetos turn away generating their spark and it keeps the engine running.

Now there are many down sides to this system including, but not limited to: manual timing, fixed ignition timing, low voltage spark, mechanical moving parts to fail, distributor blocks to get dirty, increased maintenance and inspections etc. If the timing is off, it may be slightly off due to play in the gears, or it was set incorrectly during install. This can be checked by using a timing light or timing buzzer, and a fine adjustment can be made by removing the locking pin in the magneto and rotating the magneto housing very slightly in one direction or the other to get the timing right on. All very old school and now the timing is fixed regardless of the environment the aircraft is flying in. With a traditional (classic, from the good ol'days) dual magneto ignition system the timing is set to 25°BTDC. During engine start the right magneto is grounded and the timing of the left magneto is retarded by the impulse coupling to TDC (0°). When the engine reaches 200 RPM the impulse coupling disconnects and timing falls back to 25°BTDC. When the ignition switch is released the right magneto also begins to fire. Ignition spark timing will be fixed from that point on for any RPM or altitude or any change in operating condition.

 

Why Use an Electronic Ignition?

Stronger Spark - Electronic ignition systems produce a much larger and hotter spark compared to a magneto - up to 40,000 volts versus a maximum of 17,000 volts from the magneto. This greater energy, allow spark plug gaps to be set much wider resulting in a hotter, longer length, and longer duration spark. This improves hot and cold starts as well as power and fuel efficiency.

Variable Timing - Variable spark timing improves efficiency over a wider range of operating speeds and conditions. Ignition timing automatically adjusts with altitude improving high altitude performance. Also achieving a smoother idle, efficient cruise, etc.

Multi-Strike Start - High-energy multi-strike start mode helps overcome a variety of start-up challenges (cold engine, low battery, poor mixture, oily plugs, etc.).

Fewer Moving Parts - Parts that don’t exist don't wear out. Electronic systems have no moving parts and can be expected to operate much longer, requiring less attention and maintenance than mechanical systems and therefore also reducing maintenance costs.

Better Economy/Safety - Longer spark and variable automatic spark timing optimized to RPM, manifold pressure and altitude conditions simultaneously reduces cruise fuel consumption (10% to 15% according to most of our customers) and increases horsepower. This is more than a significant fuel cost savings. It can extend your range - increasing safety margins on longer flight legs.

Longer spark plug life - due to cleaner burn and reduction in plug fouling

 

The Cons of Electronic Ignition

Two primary downsides to electronic ignition:
1.      Electronic Ignition is prone to generating kickbacks during startup due to low voltage input.
Here is how,
“If an aircraft's electrical system is weak enough (i.e. low voltage, poor ground, etc), the engine might actually rotate in a reverse direction after failing to reach the top of a compression stroke. Neither of the two well-known brands of electronic ignition systems understand this "bounce-back" problem and neither is capable of understanding that the propeller's direction of rotation has actually reversed as both systems simply count time from an index point using Hall-type sensors. Because of this limited/flawed design it is possible for both systems' sensors to misinterpret engine timing because again, neither are capable of determining the actual LOCATION of the crank/pistons - only the AMOUNT OF TIME that passes between index indicators. Either system is capable of initiating spark in a cylinder with an inappropriately located piston (before TDC) possibly resulting in a kickback.”
-(http://www.skytecair.com/EI.htm Flyweight Starters)

 That’s a pretty insulting comment and outdated as the EI’s have drastically improved over the last decade and it seems like it would take a simple remedy to fix this issue. Low voltage warning or a spare auxiliary power source.

NOTE: As I will state later in the Lightspeed discussion; Klaus, the designer, says the startup issue was remedied on his system back in 2005.

 A relevant comment from VAF Forum:

“A good thing aboutel electronic ignition is the good strong spark for starting. But timing is critical. An electronic ignition that does not retard the spark to TDC for starting is going to cause a kickback and break the starter.
 

So, conventional wisdom said its better to start on an impulse-coupled mag.

But some of the newer, better EI have a built-in spark retard for starting. The P-mags and the Light Speed ones do. Now you get the best of both worlds, a spark that is good and strong, and retarded to TDC for starting.

 

It is possible under very low voltage available to have the spark retard feature in the EI get disabled. This would be bad. You would have to have a fairly weak battery that the voltage would drop a bunch during cranking to cause that.

If you're thinking about going with the Electronic ignition, I would recommend that you install the new Kelly Aerospace "E-Drive" starter. See http://www.kellyaerospace.com/starters.html. To my knowledge, the new E-Drive is the only general aviation starter that is specifically designed to be immune to prop kick-back damage”

 2.      What happens when you have a complete electrical failure?

Well the system would stop working and the engine would quit. Wait, before you throw in the towel, there are ways around this problem like an auxiliary power source, battery or alternator, to name one. The E-Mag website discusses the risk mitigation efforts of loss of power on electronic ignitions:
“Prior to the P model, electronic ignitions addressed the risk of electrical power loss by:
    A. Installing back-up batteries, together with switching circuits, to A) engage the back-up battery when needed, and possibly B) keep the back-up battery charged. This solution:
- Adds wiring, switches, and batteries not part of the ignition kit typically provided by the manufacturer.
- Adds installation complexity.
- Adds maintenance.
- Offers a finite interval of back-up power.
- Offers marginal confidence insofar as batteries are not known for unquestioned reliability.

   B. Converting only one ignition to electronic, and maintain one magneto as a power failure back-up. This solution:
- Compromises the advantages of variable ignition timing and dual spark. Most of the time, mag timing (fixed) will fire before or after an electronic ignition using variable timing. Aircraft engines are designed for simultaneous firing from two plugs. Firing on one plug is not optimal.

A QandA from a separate site explaining how the mag spark becomes a wasted spark when coupled with an EI.
If I choose the option of one mag/one EIS, the mag has a fix firing advance and the EIS has a variable firing advance: how can this set-up work properly?

An electronic ignition always fires at 25 degrees or earlier. Magnetos are set to fire at 25 degrees, period. So the spark is already going when the mag fires and hence has very little effect.

 -Compromises the maintenance advantage of electronic ignitions. The owner has the same inspection, maintenance, and cost components as before, albeit for one vs. two magnetos.

   C. Maintaining dual magnetos and piggy-back an electronic ignition on each. In the event of electrical power loss, both ignitions can revert to magneto operation. This solution:
- Doesn't reduce the maintenance associated with magnetos. It adds what ever (minimal) attention is required for the electronic side.
- Doesn't eliminate underlying reliability issues associated with magnetos.
- Doesn't streamline the cost and complexity of the ignition package, as a whole. It makes it more complicated and much more expensive to produce.
- Requires spark plug gaps be set so magnetos are able to fire. A key advantage of electronic ignitions is the ability to increase spark plug gap to nearly double that of a magneto. You can't do that if your power back-up plan has the plug firing from a magneto. “

In the end there is a way around the loss of power issue and you can decide how to mitigate that risk. I personally don’t like the idea of having a dual system, one magneto one EI, for the reasons explained above. I would like to have a dual electronic ignition system and will explore my options for the loss of power scenario.

 

DUAL ELECTRONIC IGNITON SYSTEMS

The following is a write up on the Light Speed website explaining the advantages of a dual system.

“The benefits of installing a dual electronic ignition system are numerous. Pilots frequently asked questions regarding the benefits and specifications of dual PLASMA CDI are outlined below.

-An additional 5% gain in fuel efficiency.
When running at sea level and 2,500 rpm, a single PLASMA CDI will yield approximately 10% gain in fuel efficiency. A dual PLASMA CDI system will generate approximately 15% gain in fuel efficiency when run at the same settings. As altitude increases, fuel burn decreases and the benefits of installing a dual ignition system become more and more significant.

-An additional 2% gain in horsepower.
When running at sea level and 2,500 rpm, a single PLASMA CDI will generally produce 4% more horsepower than a mag. A dual PLASMA CDI installation will produce approximately 6% more horsepower compared to two magnetos.

-Is a back-up battery necessary?

If you are using a battery to start your engine, you have sufficient energy to run an ignition system for several hours after an alternator failure. Therefore, a back-up battery is not required when running a dual electronic ignition system. Once the system is running, less than 5V are required to maintain operation, giving a further safety cushion. At this low power level, most other electrical equipment will have long stopped functioning giving the pilot adequate warning.

If you wish to install a back-up battery for your ignition system, refer to the manual aux power supply drawing. It shows a well thought-out concept of an electrical back-up system. Should an electrical failure occur, your ignition systems will continue to run until the supply voltage drops below 5V, well past the point of all other electrical instruments. At this point the ignition systems will stop operating and the pilot can turn on the designated back-up battery. Using the prescribed wiring, only one ignition system will receive power from the aux battery to maximize your "electrical range". All electrical systems must have over-voltage protection. 

-Increased engine smoothness.When a second ignition system is installed, engine smoothness is noticeably improved.”

 

Electronic Ignition Options

P-Mag
Made by E-mag (They don’t make E-mags anymore only P-mags, but the company still holds the E-mag name.)
Summary
P-mag is self powered
Replaces the existing magneto
Not a model for the six cylinder

From Pmag website:

"Unified Form - All components (position sensor, electronics, and coil) have been consolidated in a single module that mounts cleanly in the existing magneto port. Resembling a traditional magneto, it looks "at home" on the engine. (Roughly 3 pounds and 6.25" [Lycoming] or 5.5" [Continental] long with plug wires attached).

Sealed Electronics - Sealed electronics are impervious to water, dirt, and oil. As an all-digital system, it can hold tighter tolerances through periods of significant thermal cycling.

Harness Options - Harness are available for both auto and aircraft style plugs.

Starter Motor Friendly - Like the first rule in medicine - "Do No Harm". E-MAG includes a lockout feature that guarantees the ignition will not fire before TDC during start-up. Were this to occur, an expensive starter motor can be damaged or destroyed

Voltage Reserve - Bus voltage dips sharply when aircraft starter motors are first engaged. Cold temperatures, low battery charge, and long battery cable runs all compound the problem. E-MAG is designed to endure significant voltage dips. "

Comment on VAF about the P-Mag

"I wouldn't get too optimistic about a 540 pmag. Others have tried driving a geared pickup sensor and have failed on the 540. There is a lot of ringing in the accessory drivetrain which is fine to drive a magneto but not so good for an electronic ignition. The 540 has a 1.5:1 drive ratio on the mags, which is different than the 1:1 ratio of the 4-cyl engines.”

Apparently a six cylinder model has been about to release for more than 5 years now. So I’m not holding my breath.

 

LASAR
Not in production any longer?
High CHT’s.
Could not find any data.
 

G3 Ignition

Summary
Uses existing magnetos, piggybacks original system
Timing still comes from the magneto does not change.
A multiple spark discharge not a single hot spark.

From G3 Ignition website:

“G3i is the ultimate performance aircraft ignition up grade. It is the first add on interfaced-based electronic ignition control system. The G3i interfaces with most Slick & Bendix aircraft magnetos. G3i provides redundant magneto-based ignition as a backup in case of electrical power outages or electronic ignition failure. The G3i interfaces aircraft magnetos with Electronic Multiple Spark Ignition. In turn compliments the synchronized firing event in all naturally aspirated and supercharged Lycoming & Continental engines. G3i ignition uses multiple sparking technology, which last for 20° of the crankshaft rotation.

The G3i module switches the magnetos from their typical normal state to a versatile electronic Multiple Spark (MS) ignition. This works in a way that when the G3i is on active it receives a primary signal from one of the existing magneto contact points or a magnetic crankshaft trigger, depending on the application. The most common set up is that the left magneto will become the timing signal for both magnetos when the system is active. Then the signal is then sent from the G3i module to the electronic ignition amplifier. The (MS) ignition receives this information, processes it and sends spark energy back through the G3i module to excite the left and right magnetos in perfect firing synchronization. Consequently the magnetos have all the benefits of an electronically controlled multiple spark discharge system. When the G3i module is turned off or looses its 12-volt power, the G3i switches automatically to default (no required power) and the magnetos revert back to their normal, original configuration.”

• Best Ignition Redundancy
• Uses your existing magnetos
• One system operates both magnetos independently
(Series -1 & 2)
• Interface 1 Magneto with other EI systems
(Series -SC-E)
• No need for Slick Start or Bendix Shower of Sparks
• Minimal magneto modification to upgrade your existing magnetos

• Standard shielded aircraft ignition harnesses

• Standard aircraft spark plugs
• Smoother engine operation
• Both ignitions in perfect synchronizing
• Reduced fuel consumption (up to 14%)
• Faster climb rates
• Increased horsepower
• Easy starting, hot or cold, with fouled or worn plugs
• Optional ignition retard starting programs
• MSD electronic ignition technology combined with standard aircraft ignition systems

• Multiple Spark Discharge (MSD) 20 degrees of crankshaft rotation

• Single wire modification to magneto
• Reasonable cost
• Complete G3i kit with easy to follow instructions

 

Light Speed

Summary
Magnetos removed and the opening is covered.
Need a backup system
Uses a Hall effect sensor on the crankshaft and MAP to change spark timing
PLASMA CDI (Capacitive Discharge Ignition) provides long duration spark
This long duration spark allows further leaning without lean misfiring for added fuel efficiency it also noticeably increases horsepower output and engine smoothness.
Sold from Vans Aircraft.

I called Klaus at Light Speed for a few questions:

Q. Does the 6 cylinder use the hall effect sensor?
A. Yes, one that monitors the crankcase
But it does not use the module that connects to the magneto location only the 4 cylinder engines use this.

Q. Does the system only use the DC mini sensor that mount to the crankcase?

A. And a sensor that monitors the MAP

Q. If the magneto is removed on a Lycoming engine is the vacuum pad still usable?

A. Yes, continental it is not.
 

Q. How does timing work? Is it self timing from the beginning or do you need to set it?

A. Yes, it’s based on MAP and RPM from the sensor.

Q. I heard there are start up problems with electronic ignitions. Do you feel this is still an issue?

A. Lightspeed resolved the low voltage problem in 2005.

Note:

Small 6amp hour battery will give you almost 2 hrs of flight.
The system draws 1.8amps per hour each side.
Ignition can run on alternator alone, a small backup alternator can keep you flying until the gas runs out.
Voltage regulator could stop causing a problem.

Info from Light Speed website:

•	Easy installation with built in timing light on the accessory case sensor module or a prefabricated adjustable crank sensor assembly on direct crank sensor systems.
•	Hot Spark: >130 mJ spark energy @ 0 - 3500 RPM
•	Best firing accuracy, cycle to cycle and cylinder to cylinder
•	Largest input voltage range: 5V - 35V
•	Minimum current consumption: 4-cyl: 0.5A, idle - 1.2A, cruise 6-cyl: 0.5A, idle - 1.9A, cruise
•	Light weight: CDI Ignition module: Plasma III- 1.7 lbs, Plasma II & II Plus- 1.1 lbs
•	Low "noise" makes it Storm Scope compatible
•	Best shunt resistance (fires wet and fouled plugs)
•	Aircraft Key Switch Starting available on Plasma III and Plasma II Plus
•	Discrete logic (no microprocessor) for maximum reliability: No Software & No Software Updates
•	Interconnect feature: On dual LSE Plasma III or II Plus CDI installations, the control module automatically shifts the timing curve as needed when only one system is operating.
•	Hand Starting (Armstrong Starter): Unlike other electronic ignition systems, aircraft equipped with the LSE Plasma CDI may be hand-propped.

How does the system advance the timing?
The Plasma CDI adjusts the timing based on manifold pressure (MAP) and rpm. Most of the change is based on MAP, and only a few degrees of change are based on rpm.
 

Optimized timing means more advance at lower manifold pressures and less timing advance at high power. During start, the systems fire at TDC, independent of manifold pressure.

The ignition timing is at an optimum when the engine produces peak torque. At peak torque the highest amount of energy is used for work and the least amount of energy is absorbed by the cylinder head (too much advance) or wasted in the exhaust (too much retard).

What are the power requirements for the Plasma CD systems?

The current versions of Plasma CDI systems need a minimum of 6.2 volts to start operation. This is more than 2 volts less than the minimum voltage needed by the starter solenoid, thereby eliminating the possibility of kick-backs during starter operation.

Plasma systems shipped before December 20 of 2004, need 8.5 volts to start operation. This higher "on" voltage can cause a misfire if the starter current drain is high and/or the battery is weak and the voltage collapses below this threshold during cranking. Systems shipped before 2005, can be upgraded to have the lower voltage capability.
 

Once the engine is running, all systems operate down to less than 5 volts, should you lose your charging system.

Back-up battery?

All Dual systems are shipped with a Schottky diode to be used with a back-up battery. A simple wiring diagram is also supplied.

Any aircraft with a starter has excess energy stored in the battery for starting. In flight, this large capacity is not needed. In case of an alternator failure, 17ah or more should be available. If this is only used for the ignition (2ah at 13.8v), the airplane will probably run out of fuel before the battery does. It should be standard procedure to land ASAP if there is a charging problem on an all-electric plane. Also, one of the Plasma systems can be switched off to minimize current consumption since the power is nearly the same, especially when the interconnect feature is used.

Direct Crank Sensor System

Info from Light Speed website:       
“Light Speed Engineering, LLC has developed three different devices to send crankshaft position information to the Plasma CD ignition systems. One method uses the Hall Effect Module which is installed in the accessory case and senses crank shaft position by means of the non-impulse magneto drive gear. The second mechanism is the Direct Crank Sensor system described here. The third mechanism is the Mini Sensor described on the Mini Sensor page located here.

The Direct Crank Sensor triggering mechanism is versatile and will work with most aircraft engines.

All 6-cylinder engines and all Continental engines must use the Direct Crank Sensor or the Mini Sensor.

The crank sensor circuit board has two completely independent triggering circuits if it is used for dual Plasma CDI applications. On single installations only the outer set of sensors and associated wiring harness is installed.”
 

ElectroAir EIS

Summary
Same basic idea as Light Speed
Higher voltage operation cutoff than Light Speed
sensor appears to be a little more in depth to install
Little information on the website have to read the installation manual to learn anything.

Info from ElectroAire Website:

Q. What are the voltage requirements to start and run the EIS?

A. We have systems for either a 12V or 24V aircraft. The EIS unit itself requires a minimum of 8 volts, and a maximum of 18 volts. (24V systems are regulated down to the appropriate voltage).

Q. Is a back-up battery required if I run two EIS units?

A. Yes, for dual electronic ignition, we require a dual battery system.

Q. How is the timing picked up by the controller?

A. We use a 60 tooth timing wheel, with a single magnetic pickup. The 60 tooth timing wheel provides a high resolution signal which feeds continuous RPM information to the controller and virtually eliminates timing error. For 4-cylinder Lycoming engines, the timing wheel is enclosed in our Mag Timing Housing and replaces the right-hand magneto; for 6-cylinder Lycoming engines and all other engines, we use a crank-shaft timing wheel with the pick-up mounted on a bracket.
 

Q. How does your system compare with a CD Ignition (Capacitor Discharge or CDI)?

A. The Capacitor Discharge Ignition (or CDI) does not charge an ignition coil, rather it uses the 1:100 winding ratio of the coil as a transformer. Initially, the 12 volts of the electrical system is converted to 200-500 volts and stored in a capacitor. When the spark is required, the capacitor is discharged into the ignition coil instantly producing a spark with duration of only 0.1 to 0.3 milliseconds. For many applications this spark duration is not long enough to ensure that the air-fuel mixture ignites completely. A multiple coil ignition system, like the Electroair EIS solves this problem by using an ignition coil for every pair of companion cylinders. The time available to charge an ignition coil goes up. This allows the full benefit of an inductive charging method to be realized: the coil

 

EFII flyefii.com 

Summary
Same basic idea as above
Do have a complete electronic fuel injection available but that is something for another day. Right now I’m just looking into electronic ignitions that are available.

Infor from Flyefii website:
“We have taken the core control system of the EFII fuel injection system and pared it down to the ignition components. This allows us to offer a dual mag replacement high energy ignition system for your aircraft. And what is unique about that you ask? Well, the EFII system uses a very high energy inductive coil pack to deliver several times the spark energy of the most popular competitor system for more complete combustion. Secondly, once you have installed one of our ignition systems, you have opened the door for an easy upgrade in the future to the full electronic fuel injection and ignition EFII system. You can start now with a single or dual mag replacement ignition that utilizes our billet Hall effect crank trigger and proven engine computer and simply add the rest of the EFII fuel injection kit in the future if you choose to do so. This easy migration path between systems can not be matched by any other ignition or fuel injection company.”
 
The EFII Dual Mag Replacement Ignition Kit includes:
- Ignition computer.

- High energy coil packs with integral magneto block off plate.

- Billet Hall effect crank trigger (no case drilling required).

- High quality silicon spark plug wires, 8ea.

- Automotive Iridium spark plugs, 8ea.

- Spark plug adapters, 8ea.

- MAP sensor.

- Tefzel plug and play wiring harness with environmentally sealed connectors.

 

We have put together the highest quality components in these systems to give you the best available performance and reliability.

 

Conclusion

At the end of all this research I have learned quite a bit about Electronic Ignitions for the six cylinder engine. The benefits drastically out way the cons of having an EI. The maintenance and fuel savings alone are worth the relatively small increase in cost and work required to install this system. As of today, March 2013, I am strongly leaning towards the Light Speed system. The information on the website, history, accessibility, and the discussion with Klaus sold me on the system. Researching all of this has been very helpful to me and my decision making. I highly recommend completing your own due diligence when selecting your ignition system.